(1) Field of The Invention
This invention relates to a mechanical penile prosthesis, to its manner of construction, and its use for the treatment of erectile impotence or as a functional component of a penile replacement prosthesis.
(2) Description of The Prior Art
Impotency is not only psychologically based, but can be related to nerve or vascular damage that may have been caused by severe diabetes, multiple sclerosis, spinal-cord injury or surgery in the lower abdomen, such as removal of bladder or for rectal cancer. It can also be the result of advanced age, trauma, and the side effects of drugs.
One surgical treatment for impotence involves, in particular, that caused by circulatory ills, revascularization, a technique developed by vascular surgeon Harry H. LeVeen of Brooklyn, New York. And while this technique has proved fairly simple, and apparently quite successful, it is limited to impotence that is caused by circulatory problems. Accordingly, it cannot be used to help patients with psychogenic or neurogenic impotence.
Another procedure that is being adopted more-and-more by surgeons for erectile impotence is penile prosthesis. This treatment is being used not only for impotence caused by age, disease, radical surgery, etc., but is also being used for psychogenic erectile impotence, but only after careful patient evaluation, generally when conventional sex therapy fails.
The modern era of penile implants is but five years old, spawned by development of two new, though very different, prostheses. One emphasizes simplicity, both of surgery and function, but gives the recipient a permanent erection. The other offers the patient a choice of flaccidity or erection but is costlier, more complex, and more prone to mechanical problems.
The simpler prosthesis was developed by Drs. Michael P. Small and Herman M. Carrion of the University of Miami School of Medicine. It consists of a rod-like device with a silicone sponge interior encased in a medical grade silicone exterior. It is implanted in pairs within the crura and the corpora cavernosa.
The more sophisticated prosthesis was introduced by Dr. F. Brantley Scott, Professor or Urology at Baylor College of Medicine in Houston. It is a totally implantable device using paired inflatable silicone cylinders within the corpora cavernosa connected to a hydraulic pumping device implanted in the patient's scrotum. The fluid reservoir for pumping pressure is placed behind the patient's rectus muscle.
In the impotent patient, the flow of blood to the penis' blood vessels is impaired. The increased flow is necessary for the tissue surrounding the vessels to expand and cause erection. A prosthesis, or artificial device, that causes erection is surgically inserted into the cavities of spongy tissue in the penis. It is these two cavities that normally fill with blood during erection.
With the inflatable device, an inert fluid takes the place of the blood supply. Two inflatable silicone tubes are inserted along the side of the penis' spongy tissue. The cylinders are attached by small tubes leading to a fluid-filled sac, which is implanted under the patient's lower abdominal muscles. By manipulating the small valves placed under the skin of the scrotum, the patient may fill or empty the penile cylinders with fluid, thus causing erection, also called tumescence, or detumescence.
The big advantage of the inflatable device, over the permanently hard silicone rods, is aesthetic--the patient does not have a permanent erection--but insertion of the device requires a more major operation, and there are more post-operative complications. The surgical insertion of an inflatable prosthesis, moreover, generally precludes the ability to have a normal, unaided erection, although this is not usually true with the non-inflatable device.